Method and apparatus for indicating the level of liquid in a tank



.sept-16.1924. 9 y K l 1,508,969

l l.. Gulex-IARD HETHODAD APPARATUS FOR INDIC ATINGI THE LEVEL 0F LIQUID INVA TNK Filed may 31, 1922 Patented sept. 1c, 1924'.

` 1,508,969. A PATENT OFFICE.-

LOUIS GUICABD, OF PARIS, FRANCE, ASS'IGNOZR. T0 EDOUARDSHGNOL, 0F' PARIS,

FRANCE'.

- METHOD AND APPARATUS FOR INDICATING THE LEVEIZI` OF II'AIQUIZDy IN' A TANK.

replication mea may 31, 1922. serial No. 564,978.

To all 'whom t 'may cof/wcm.' f Be it known that I, LoUIs GUICHARD, a French citizen, and a resident of 1, Avenue de Peterhoi, Paris, France, have invented' certain new and useful Improvements in Methods and Apparatus for'lndicating the Level of Liquidin a -Tank (for which I have filed anv application in France No. 536,-

.distance the volume of liquid contained in "a tank. It is particularly applicable for tained in a tank, but upon the measurement l use on automobile vehicles and serves to indicate to the driver, withoutthe necessity of him leaving his seat, the quantities of petrol and oil remaining in the tanks. Y

Various apparatus'V have been suggested hitherto for. indicating the level of llquids in tanks to the driver, but in general the results obtained are not very accurate. Apparatus depending upon the pressure of air necessary for balancing a column of liquid of .a given height give indications which necessarily vary with the density of the liquid. Moreover different qualities of liquid and diferent liquid fuels have very different densities, thus for example the difference between the density of petrol and the density of benzol is about 20%. Moreover such apparatus fails in accuracy by reason of the small height of the balancing liquids and in consequence of the movements of the liquid during running in consequence of its inertia. a

The apparatus using a float are complicated and require eitherl the use of mechanical c/ontrols or the use of a source of electricity and a resistance for transmitting their indications to the front of the vehicle. Finally none of the apparatus at present in use permits of correctly indicating the level of oil contained in the casing or in ther` tank'of the motor for the lubrication thereof by reason of the viscosity of the oil which lends itself very poorly for use in connectionwithexisting systems.

The process forming the subject ofthe present invention obviates these disadvantages. It is based,` not upon the dlrect measurement of the volume of liquid conof the volume of air contained in the tank above the level of the liquid. These two 1 pipes is neg which being known, the other can lbe easily determined. VIt will be seen thatl the result I volumes having a constant total, one of obtained is necessarily independent of the l denslty and of the viscosity of the liquid\ and also of the movements which the liquid is liable to make in the tank.

In the accompanying drawings there are illustrated diagrammatically by way of example various arrangements for carrying lnto eii'ect the process forming the subject of the invention. ra Figure 1 is a theoretical diagram adapted to serve Vfor the explanation of this process.

Fig. 2 is a modiied form of Fig. 1.

F 3 shows aMform of the device in operatlve position.

1 represents a tank partly filled with liquid, provided at its lower endwith a tap 2 through which ,it can be discharged.

measure the vo ume of liquid remaining in the tank. For this purpose the valve 6 is placed in such a position as to bring the tank 1into communication with the-pump 7 and the gauge 8 and to disconnect itfrom the'atmosphere. The tap 2 is closed. The piston of the pump is operated so that it is moved into the position 10. Thel gauge 8 which was at O rises and indicates a pressure P which gives the measurement of the volume to be found. For example if V-'is the volume of the tank between the level of the liquid and the cover (that is to say the volume of air enclosed inthe tank), 'D

the volume of the pump cylinder, p thel atmospheric ressure and the volume of the ected, Boyles law gives the PV: (F4-o) Xp.

In practice p remains constant and can be considered equal to 1, this gives equation.

This giving It will be seen that the value of V corresponds, after compression, to a given value of P; it is thus possible with a glven tank and pump, to graduate the gauge, not .5 in pressures, but inl volumes\land to 4read tly on this gauge the volume of liquid remaining in vthe tankl.

`It may here be mentioned that if the volume of the tank is very large nbrelation to the capacit of the pump the tlme will soon 'arrive w en emptying the tank, tllgix'jdications of the gauge -will show d1 e'venc'e for variations in large volumes oftgluid. This defect is remedied as indic a in Figure 2 by connecting the tank .1 to a receptacle 11 -of which the volume 1s more nearly equal to that of the capacity of the pump. After having closed the tape between 1 and 11 the volume of liquid in the rece taclell will be measured in the manner ereinbefore described and thus Vof the liquid contained in the tank 1, the levels of the liquids in the tank and the receptacle Being the same.

In Figure 3 .is'illustrated an arrangement Y for into effect-the process which has beendescribed.

Within reach and within the view of the driver there are placed the pump 7 and the gauge 8. These two devices are connected together by a pipe 16 and communicate with thetanklbyapipe17.b`

The ump contains a piston 12 held at the en of its stroke by -a spring 13 which r.may be compressedwhen pressing upon the ture 15 1s provided in the pump in suc a manner that it is closed when the iston {1s-operated but 'normally connects t e -in- .tenor-pf e ump and consequently also f the gauge an the receptacle 11 with the f lThe tank-.1 communicates directlywth ,1. means of ,a perforated pl 1s ,provided with a mem cured-.tothe upper will of the-miki and j ...to nearthebetwm thereof., The 'be 131e atits two In 4thezupper jlaghol'e 1s formed-at-19to which is' c'on;

#with a conical "criicel .at

a'zlightfwasher-21 provided on vit'sunderf' l '.va'lve'is msured `by a 23' p assmg" v through 'Libya 'sp 25.QThe-levelfof liquidfin the` oewi'th'thepl'inti l :gintercommunicatin vessels,` 11 :itidei .f f qfphquid comme in the me; V.1' 'it h littl piston by means of the knob 14. An a r- .'l'edillg 0f the theatmosphere in the usual manner td The vmember ls-formdg'of lL- tuba 18 the pipe 17. .The lower midi,

e'rice forms seatof` afl valve 'eonipoeedj Y the-tank 1 and sim ly communica ftherewithorby' an auxl 'ary to'one ofthe walls of the main tank with- 'arcross member 24.' vThe valvejiebalanced with a .com #The guiding brebis vclum the left-hand end in the drawing. The piston first closes the orifice 15 and thus shuts off the communication of the tube 11 with the atmosphere. As soon as the piston has passed the orifice 15 a slight pressure com-A mences to be reduced in the ipe 17 and this is transmltted to the li u1d contained in the tube 11, thus causing t e valve 21 to bel closed upon its seat 20. The contents of the tube 11 are thus completely enclosed as no communication is open either with the atmosphere or with the tank 1. At the end of the movement of the piston the pointer of the gauge 8 assumes a'position whlch willv only depend upon the level of the liquid in the tube 11 and consequently upon the level of the liquid in the tank 1. By suitably graduating the gauge is is possible to read directly on lthis instrument the volume of 1i uid enclosed'in the tank 1.

en the pressure on the knob 14 is removed the spring 13 returns the piston 12 to its ori inal position and restores communication tween the receptacle 11 and the atmos here. As the pressure in the receptacle 1s thus reduced to .atmospheric pressure, the spring 25 opens the valve 21 and the whole arrangement is again ready for making a fresh operation for measuring the volume of liquid in the tank 1.

The apparatus which has been described is simple fool-proof and is not provided with any complicated mechanism. The gauge is eected with the greatest easewwithout any delicate operations, :and is instantaneous. As hereinbefore stated the nature or the viscosity of the liquid does not in any way afect the accuracy. ofthe apparatus.Y Moreover the graduation of ,the gauge for a particular apparatus will serve indefinitely iny the various densities of liquids whi may be`-"eontained infthetank i vIt willgof course' be understood thatthe mvention'i lvnotli'mited, to the particular Ifor. 'example -thepo'eitions of the pump 7, the

gauge ithdles for isolating the auxiliary tankk 11-fromthe main .tank 1 and with 'ftheatmos'phereina be varied. It is n.180

` ible for exam'p etofieplace the tube 11V 'y an auxiliary tank vplaced at a tank i out departing'from'the spirit of the inven-l igure'' may also serve easuringythe volumeijo'f contained in -measuriiig-thevolume'of petroLj-f:

ite of'V form @fliege-swim described. vtriouafl 'mod ifiaeensmsyfbe mae. in the deuils,

iis

suitable-tank vin-av similar manner as for -ters Patent is l. A process for measuring the volume of liquid contained in a tank, such as the tank lof an automobile vehicle, comprising tem.

porarily isolating a body of. air so enclosed above the level ofthe liquid, that its volume will vary inversely as such level varies,l and in adding to the said body of air, a constant quantity of air so as to increase the pressure of the# enclosed air, and measuring the resulting., increase in pressure on a gauge graduated in units of volume.

)2. An apparatus for determining the volume of liquid contained in a tank comprising a tank, a perforated plug in said tank, a tube mounted in said tank, avvalve seat formed at the lower end of said tube, a valve (1o-operating with said seat, means normally holding the valve away from said seat, means for guiding said valve, a pump, a

gauge graduated in volumes, pipes connect,

lng said lgauge and said pump to the upper end of said tube, said pump having an ori- -fioe therein normally connecting the interior of the pump with the atmosphere, a piston in said pump, a knob connected to said pump said piston when operated being adaptedto close said orifice and to apply pressure to the interior of the tube so as to close the valve in said tube and to produce a movement of thegauge, and a spring, said spring serving to return the piston to its normal position.

LOUIS GUICHARD. 

